Self-injurious behavior is a chronic disorder that poses serious health, social, and educational risks to a substantial proportion of developmentally disabled children, and it is one of the most difficult to treat problems found in that population. While various behavioral procedures have been demonstrated to effectively reduce this disorder, systematic research has not been conducted on the motivational variables that maintain self-injury, it's causes, or a comparison of the various methods of remediation. Over the past several years, we have been developing an experimental Model for the assessment and subsequent treatment of self-injury. The results of this work indicate that self-injury is differentially affected by various environmental events, and suggest that response differentiation is associated with several potential sources of motivation. Additionally, the treatment strategies resulting from this assessment have been shown to reduce self-injury. The proposed research will extend our current work on the assessment and treatment of self-injurious behavior. Our specific aims are: 1) To refine our assessment methodology and to apply it to a large sample (N = 50+). 2) To conduct comparative research on the treatment of escape-motivated self-injury. 3) To evaluate the effects of a multi-component treatment program. 4) To conduct generalization research on the effects of punishment on self-injury. 5) To examine the phenomenon of self-restraint. This research will form the core research program of a center being established specifically for the treatment of self-injurious behavior. These studies will serve as the basis for continuing our experimental investigations on the etiology and treatment of self-injury.